Ensure that constant-capacity elements are initialized on copy

R=ishell@chromium.org

Review URL: https://codereview.chromium.org/308003015

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21728 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index df83f04..c7acf95 100644 (file)
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -2576,6 +2576,17 @@ void HGraphBuilder::BuildCopyElements(HValue* from_elements,
     }
   }
 
+  bool pre_fill_with_holes =
+    IsFastDoubleElementsKind(from_elements_kind) &&
+    IsFastObjectElementsKind(to_elements_kind);
+  if (pre_fill_with_holes) {
+    // If the copy might trigger a GC, make sure that the FixedArray is
+    // pre-initialized with holes to make sure that it's always in a
+    // consistent state.
+    BuildFillElementsWithHole(to_elements, to_elements_kind,
+                              graph()->GetConstant0(), NULL);
+  }
+
   if (constant_capacity != -1) {
     // Unroll the loop for small elements kinds.
     for (int i = 0; i < constant_capacity; i++) {
@@ -2586,17 +2597,8 @@ void HGraphBuilder::BuildCopyElements(HValue* from_elements,
       Add<HStoreKeyed>(to_elements, key_constant, value, to_elements_kind);
     }
   } else {
-    bool pre_fill_with_holes =
-      IsFastDoubleElementsKind(from_elements_kind) &&
-      IsFastObjectElementsKind(to_elements_kind);
-
-    if (pre_fill_with_holes) {
-      // If the copy might trigger a GC, make sure that the FixedArray is
-      // pre-initialized with holes to make sure that it's always in a
-      // consistent state.
-      BuildFillElementsWithHole(to_elements, to_elements_kind,
-                                graph()->GetConstant0(), NULL);
-    } else if (capacity == NULL || !length->Equals(capacity)) {
+    if (!pre_fill_with_holes &&
+        (capacity == NULL || !length->Equals(capacity))) {
       BuildFillElementsWithHole(to_elements, to_elements_kind,
                                 length, NULL);
     }